How do you explain to siblings something should be done now, not wait and see in 6 months?

One danger of "gifting" like this, besides the obvious damage to any chance the recipient has of ever standing on his own two feet, is that it would cause a penalty period if she ever needs Medicaid. But, unless she is legally not competent or at least documented incapacitated under the terms of your POA it is her right to do that. You need more of an evaluation of her ability to care for herself and her mental status to help decide - and no, waiting 6 months does not strike me as a real good idea either. Resources for evaluations inlcude Adult Protective Services if you think the home is hazardous and/or lacking in basic necessities, a geriatric or senior comprehensive care program maybe affiliated with a university, Area Agency on Aging could be a contact for advice if not more direct assistance.

Petition for Guardianship as soon as possible.

So what if she fights like a child? You and your siblings have to step in and do the right thing anyway, like it or not. Mom has changed, and her arrangements need to change to match her abilities. You guys have got to buck up and see past the manipulation tricks, like verbal abuse. This is going to require a steel spine transplant to get through.

What mom wants, and how she prefers things comes on the list right after all her safety and wellbeing needs are met. Safety trumps everything.

You cannot leave a person with dementia alone. There is not a competent doctor or social worker who would say yes to that. Knowingly letting this happen is a bad position to be in.

Take away her checkbook, her ATM card, and anything that would allow her to spend money. You go over there, and collect everything. Take it home and put it in a safe. Or put it in a safety box at the bank. This is not a polite request. You sit her down and say there's been some problems with her money, and you have to have all her forms of payment to look into it. The end. No discussion. Put it all in a big ziploc bag, and it never leaves your hands again.

Assuming one of you has the power of attorney document, take that to the bank, and have every check issued to that nephew investigated.

This nephew may need to understand that he could be on the hook for fraud.
Fraud is real and fraud charges can happen to him. You can talk to the police about this, and find out how to get that money back for her care. So what if he's family. I sure as snot wouldn't just let that kind of money go. If she signed checks to him while incompetent, there's a problem.

Yes, people with dementia can be mean as a snake and twice as difficult. You are going to have to be mentally prepared to deal with it. You have to be the adults and make good decisions no matter how badly mom acts. Her brain is sick, and she can't control it anymore.

Talk to her doctor about her behaviors. Agitation and combativeness can be helped with different medications, but she might need to be somewhere supervised 24/7 for her own safety.

This site has all the where-to-start information you're going to need. Lord knows I did. Find the New to Caregiving section and read the articles.

Come back with questions, and this community is amazing with its knowledge & support! You're going to need it!

Call the Area Agency on Aging and have her assessed if they'll do that. See what they recommend. What does her doctor say about her living on her own?

If she's diagnosed as malnourished and you don't do anything about it, I'd be concerned (as her POAs) that you and/or siblings could be held accountable for elder neglect. If she has dementia, which your profile says she does, she's not in her right mind. What she wants isn't as important as what she needs to be safe and healthy. She's not able to make those calls on her own with dementia.